The present invention relates to airfeed peck drills more particularly the present invention relates to nose pieces which are used to mount drill bushing tips on the end of airfeed peck drills.
Airfeed peck drills are typically used in the aircraft industry where it is necessary to drill accurate holes with a smooth internal finish. Such results are obtainable with controlled drill feed. Controlled drill feed is accomplished by attaching an air cylinder to the back of an airfeed drill so that air pressure may be used to push against a piston in the air cylinder thus causing the rotating drill to move into the workpiece.
A more sophisticated airfeed drill is an airfeed peck drill. Herein air pressure is used to first push the rotating tool into the workpiece and then fully extract it from the workpiece then repush it into the workpiece then reextract it again. This pecking occurs numerous times over the period of time required to drill a hole. Such pecking operation allows for drilling holes and obtaining accurately sized holes and better internal hole finishes.
One method of mounting airfeed drills to workpieces for drilling holes involves the use of drill bushing tips attached to nose pieces extending from air feed drill housings. The rotating drill passes through the drill bushing tip. In one type of drill bushing tips a cam collar on the outside of the drill bushing tip allows the drill bushing itself to be passed under two cam follower posts attached to a fixture which is attached to the workpiece. This enables the airfeed drill to be properly positioned with respect to the workpiece. Drill bushing tips are commonly marketed by such companies as United Drill Bushing Corp.
Before a hole is drilled, a fixture with cam follower posts is placed over the hole entry point. The air feed drill is then positioned by placing the drill bushing tip between the cam follower posts. The drill is then twisted when the drill bushing tip is located between the cam posts. The cam collar surfaces formed on the outside of the drill bushing tip enable locking of the drill bushing tip to the fixture and thus the drill is positioned with respect to the workpiece.
Housings which mount drill bushings tips have always been a semi-permanent part of the overall tool housing. For rigidity housings have been threadably connected to the drill housing. Changing housings meant partial disassembly of the tool. This operation is time consuming and often requires that the tool be pulled out of production to change housings.
There is therefore a need in the art to provide an airfeed peck drill with nose piece housings which may be removed and replaced in a minimum amount of time.